Map display system for vehicle navigation

ABSTRACT

A map display system includes a vehicle symbol positioned in relation to background map data, and provides a large amount of relevant, easy-to-read map data to a user in a brief period of time. A first feature of the invention involves the drawing of aircraft landing and take-off areas in true size and orientation relative to background map data. A second feature involves display of navigation control areas in relation to an aircraft symbol. In accordance with a third feature, a user can select for display only objects meeting preselected criteria, such as airports having runways of a minimum length. A user can select an object for which text appears on the screen adjacent to that object and which may indicate relative position or distance to such object from the vehicle, in accordance with a fourth feature. A user can select full screen text of information concerning an object on a screen display, in accordance with a fifth feature. A sixth feature provides an automatic alert for an increased oncoming minimum safe altitude for aircraft flight. In an seventh feature, background map data is held stationary while a vehicle symbol moves in relation to the background map data. An emergency aircraft mode of operation, in accordance with an eighth feature, causes automatic display of at least a predetermined number of suitable landing sites according to preselected criteria, such as minimum runway length. A ninth feature involves display of planned and actual travel patterns of a vehicle.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to map display systems to aid in vehiclenavigation, and more particularly to such systems which receive positionand direction of travel data for a vehicle and provide a symbol on ascreen display to show location and direction of the vehicle relative tobackground map data.

Map display systems have been used in the past to aid in navigation ofan automobile or other land-based vehicle. Such systems incorporatemeans to determine the position and direction of travel of the vehicle,and show a vehicle symbol in relation to background map data.

Users of the known map display systems for navigation of a land-basedvehicle typically have ample time for observing the map display. Fornavigation of an airborne vehicle, however, the pilot often has scanttime to contemplate map displays. To meet the needs of a pilot, a mapdisplay system should convey to the pilot a maximum amount of relevant,easy-to-read information in a brief period of time.

It is, accordingly, a main object of the invention to provide a mapdisplay system that is particularly useful for navigation of an airbornevehicle.

A further object of the invention is to provide a map display system foran airborne vehicle conveying to the pilot a large amount of relevant,easy-to-read information in a brief period of time.

It is a further object of the invention to provide a map display systemwith safety features tailored for navigation of an airborne vehicle.

In accordance with a first feature of the invention, a map displaysystem is provided for navigation of an aircraft showing landing andtake-off areas in true size and orientation in relation to backgroundmap data. The system comprises memory means to store map data of an areain which the aircraft may travel. Such data includes reference points oflanding and take-off areas in one memory location and true size andorientation of the landing and take-off areas in another memorylocation. A first means composes a first image component of a symbol forthe aircraft. A second means selectively collects map data from thememory means and composes a second image component of such data. Meansare provided to receive position and direction of travel data for theaircraft and to determine placement of the first image componentrelative to the second image component. A third means selectivelycollects from the memory means map data of true size and orientation oflanding and take-off areas within the range of the second imagecomponent and composes a third image component of such landing andtake-off areas aligned with and in true size proportion to the secondimage component. A display means is provided to collectively display thefirst, second and third image components.

In accordance with a second feature of the invention, a map displaysystem for navigation of an aircraft shows navigation area boundaries,such as terminal control areas, in relation to the aircraft. The systemcomprises memory means to store map data of an area in which the vehiclecan travel. Such data includes boundaries of navigation areas. A firstmeans composes a first component of a symbol for the aircraft, whereasthe second means selectively collects map data from the memory means,including data of navigation area boundaries, and composes a secondimage component of such data. The system includes means to receiveposition and direction of travel data for the aircraft and to determineplacement of the first image component relative to the second imagecomponent. A display means then collectively displays the first andsecond image components.

In accordance with a third aspect of the invention, a map display systemis provided for navigation of a vehicle with display of objects meetinguser-selected criteria. The system comprises memory means to store mapdata of an area in which the vehicle may travel. A first means is usedto compose a first image component of a symbol for the vehicle; and asecond means is used to selectively collect map data from the memorymeans of objects which meet user-selected criteria and composes a secondimage component of such data. The system includes means to receiveposition and direction of travel data for the vehicle and to determineplacement of the first image component relative to the second imagecomponent. A display means is used to collectively display the first andsecond image components.

A fourth feature of the invention provides a map display system fornavigation of a vehicle showing text on map data for a user-selectedobject. The system comprises memory means to store data of objects in anarea in which the vehicle may travel and also of text data concerningobjects in the map data. A first means is used to compose a first imagecomponent of a symbol for the vehicle, and a second means is used toselectively collect map data from the memory means and to compose asecond image component of such data. The system includes a means toreceive position and direction of travel data for the vehicle and todetermine placement of the first image component relative to the secondimage component. A third means selectively collects data concerning auser-selected object from the memory means and composes a third imagecomponent based on such data and including text of such data. A displaymeans collectively displays the first, second and third imagecomponents.

A map display system for navigation of a vehicle, in accordance with afifth feature of the invention, shows text concerning a user-selectedobject. The system comprises memory means to store map data of an areain which the vehicle may travel, and of text data concerning objects inthe map data. A first means is used to compose a first image componentof a symbol for the vehicle, and a second means is used to selectivelycollect map data from the memory means and to compose a second imagecomponent of such data. A means is used to receive position anddirection of travel data for the vehicle and to determine placement ofthe first image component relative to the second image component. Athird means is used to selectively collect from the memory means textdata concerning a user-selected object and to compose a third imagecomponent including such text data. A display means is used toalternatively display, at the command of the user, the first and secondimage components, collectively, or the third image component includingtext.

A sixth feature of the invention provides a map display system fornavigation of an airborne vehicle with an alert for an increasedoncoming minimum safe altitude. The system comprises memory means tostore map data of an area in which the airborne vehicle may travel. Suchdata includes minimum safe altitude information. A first means is usedto compose a first image component of a symbol for the vehicle, and asecond means is used to selectively collect map data from the memorymeans and to compose a second image component of such data. Means areused to receive position and direction of travel data for the vehicleand to determine placement of the first image component relative to thesecond image component. A fourth means is used to scan minimum safealtitude information in a first range including the vehicle and tobroadcast an alert when an upcoming minimum safe altitude exceeds thatfor a second, smaller range including the vehicle by a predeterminedamount.

A seventh aspect of the invention provides a map display system fornavigation of an airborne vehicle showing a moving aircraft symbol on astationary background. The system comprises memory means to store mapdata of an area in which the vehicle may travel. Such map data includesa user-selected waypoint. A first means is used to selectively collectfrom the memory means map data including the user-selected waypoint andto compose a static first image component of such data with the waypointcontained in the first image component and the first image componentoriented in a predetermined direction. A second means is used to composea second image component of a symbol for the vehicle, including means torepeatedly recompose the second image component to show vehicle movementrelative to the first image component. The system includes means toreceive position and velocity data for the vehicle and to determine theplacement of the first image component relative to the second imagecomponent. A display means collectively displays the first and secondimage components.

An eighth feature of the invention provides a map display system fornavigation of an airborne vehicle with emergency display of nearestsuitable landing sites. The system comprises memory means to store mapdata of an area in which the vehicle may travel. Such map data includessymbols of and text concerning landing sites and navigational aidsidentified by respective criteria. A first means is used to compose afirst image component of a symbol for the vehicle. A second means isused to selectively collect from the memory means map data including atleast a predetermined number of suitable landing sites, determined onthe basis of user-select criteria. The second means also is used tocompose a second image component of such data. The system includes meansto receive position and direction of travel data for the vehicle and todetermine placement of the first image component relative to the secondimage component. Display means are used to collectively d splay thefirst and second image components.

In accordance with a ninth aspect of the invention, a map display systemfor navigation of a vehicle shows an actual travel pattern of thevehicle. The system comprises memory means to store data of an area inwhich the vehicle may travel, first means to compose a first imagecomponent of a symbol for the vehicle, and second means to selectivelycollect map data from the memory means and to compose a second imagecomponent of such data. The system includes means to receive positionand direction of travel data of the vehicle and to determine placementof the first image component relative to the second image component. Athird means, responsive to the first means, stores data of and composesa third image component of an actual travel pattern of the vehicle, andrepetitively updates such data and recomposes the third image componentas the vehicle travels. A display means is used to collectively displaythe first, second and third image components.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects as well as other objects of this invention shallbecome readily apparent after reading the following description of theaccompanying drawings in which:

FIG. 1 is a block diagram of a microprocessor-based hardware system thatmay be used in carrying out the features of the present invention;

FIGS. 2A and 2B show typical screen displays for illustrating thedisplay of landing and take-off areas in true size and orientation inrelation to background map data;

FIGS. 3A and 3B show a flow chart used to implement the features ofFIGS. 2A and 2B;

FIG. 4 shows a screen display with navigational areas, such as aterminal control area, in relation to an aircraft symbol;

FIGS. 5A and 5B show a flow chart used to implement the features of FIG.4;

FIG. 6A illustrates a cluttered screen display, whereas FIGS. 6B and 6Cillustrate the same screen display but showing only objects selected bycriteria;

FIG. 7 shows a flow chart used to implement the features of FIGS. 8B and8C;

FIG. 8A shows a typical screen display, whereas FIG. 8B shows textprovided in a box adjacent an airport, and FIG. 8C similarly shows textprovided in a box near a navigational aid;

FIGS. 9A and 9B show a flow chart used to implement the features ofFIGS. 8B and 8C;

FIGS. 10A and 10B show typical, full screen text information of alanding facility and a navigational aid, respectively;

FIGS. 11A and 11B show a flow chart used to implement the features ofFIGS. 10A and 10B;

FIG. 12 shows a screen display with an alert for an increased oncomingminimum safe altitude;

FIG. 13 shows a flow chart used to implement the features of FIG. 12;

FIGS. 14A and 14B illustrate screen displays with background map dataheld stationary, and a symbol for the aircraft that moves with respectto the background map data when in the displayed range;

FIGS. 15A and 15B show a flow chart used to implement the features ofFIGS. 14A and 14B;

FIG. 16A shows a typical screen display, with a first displayed range,whereas FIG. 16B shows an emergency mode screen display at a different,automatically selected range including a predetermined number ofsuitable landing sites and also text of relevant navigationalinformation;

FIGS. 17A and 17B show a flow chart used to implement the features ofFIG. 16B; and

FIG. 18A shows a screen display with an aircraft symbol approaching apreselected flight pattern, whereas FIG. 18B shows the same vehiclesymbol and a path of its actual travel pattern after it has followed aportion of the preselected flight pattern.

DESCRIPTION OF THE PREFERRED EMBODIMENTS System Hardware

The present map display system is preferably implemented on amicroprocessor-based computer system, such as shown at 10 in FIG. 1.System 10, which is typically contained on a single printed-circuitboard may include, by way of example, the following features:

(1) A 68000 32 bit microprocessor 12 running at 10 MHz.

(2) 128 Kbytes of system ROM 14.

(3) 128 Kbytes of RAM 16.

(4) Two RS-232C ports 18 and 20, one of which (18) has an opto-isolator22 in its input.

(5) High resolution, bit-mapped graphics cathode-ray tube (CRT) displaycontroller 24.

(6) A real-time clock 25 with a battery (not shown) for continuousoperation.

(7) Non-volatile RAM contained in block 25 for storing installationsettings and display options.

(8) Connections 26, including four for front panel switches.

(9) A mini phone jack 28a, 28b for cassette upload and download.

(10) Eight analog inputs 31 from a connector 32 to an eight bitAnalog-to-Digital (A/D) converter 34, with one input dedicated tocassette input 28b.

(11) Connectors for a "piggy back" memory board 36 with backup batterypower.

Microprocessor 12 is a 16/32 bit machine. Data bus 15 is 16 bits widebut the internal registers are 32 bits. Thus, microprocessor 12 allowsarithmetic operations to proceed either 8, 16 or 32 bits at a time.

Most of the address decoding functions in system 10 are performed by aDecode Programmable Array Logic (PAL) 38. This is a 20L10 type devicewhich contains a large number of undedicated logic devices. Theseundedicated devices are configured by a PAL programmer so that they willperform a specific set of logic functions. Specifically, the PAL looksat the address bus 39 and control signals 40 and generates "Chip SelectSignals" for the various chips and devices in the system.

The software that microprocessor 12 executes to perform all thefunctions of system 10 set forth below resides in system ROMs 14. Alsocontained in these ROMs are the vectors, system constants and other datathat microprocessor 12 requires in order to perform its assignedfunctions.

Input/Output (I/O) registers 42 are composed of two chips: a 74HCT244Octal Buffer and a 74HCT273 Octal Latch. When microprocessor 12 accessesthis area of the address space, one of these two chips are selected.Which chip is enabled depends on whether a read or write is being done.The I/O registers 42 allow microprocessor 12 to read external conditionssuch as may be provided by front panel switches, as well as to controlthe operation of an Analog Multiplexer (MUX) 43 and cassette output 30.

A 68681 Dual Universal Asynchronous Receiver/Transmitter (DUART) chip inblock 44 provides communication between system 10 and other instrumentsin an aircraft. Such communication is done via RS-232C serial datatransfer protocol. "RS-232C" data is that provided as an output by acommercially-available LORAN C receiver, a known device, operating inaccordance with an industry standard, and providing vehicle position anddirection of travel data to a "monitored" aircraft. DUART chip 44handles most of the work in providing communications. A crystal in DUARTchip 44 provides basic timing for the baud rate generator section ofDUART chip 44 which times the arrival and transmission of individualbits of serial data Opto-isolator 22 allows the LORAN receiver,navigation computer or other data sources in an aircraft to beinterfaced to system 10 without direct electrical connection to thesystem circuitry. Thus, any failures within system 10 should not disruptthe operation of other devices on the aircraft. An RS-232Creceiver/driver chip 44 comprises a MAX 232 chip and contains circuitryto convert the +5 volt system power to +/-10 volts to drive RS-232Cbusses 20.

Real-time-clock 25 performs a number of functions for system 10. Itmaintains the current time of day and current date; generates a streamof timed interrupts; contains 32 bytes of non-volatile RAM; generates aso-called /RESET signal for initializing system hardware when power isapplied; and contains a so-called "Watchdog Timer" to generate a resetcommand for bringing the system to a functioning state after thesoftware ceases to function.

In system 10 one set of dynamic RAM (DRAM) chips 16 are shared betweenthe microprocessor and the display. DRAMs 16 are controlled by acontroller 46, which includes a DRAM control PAL to handle all decoding,timing and arbitration logic to control the DRAM. Controller 46 alsoincludes a RAM address multiplexer. A 6845 CRT controller 24 generatestiming for a CRT display and for addresses for the RAM data to bedisplayed on the CRT screen.

DRAMS 16 contain, for example, a bit-mapped image shown on a displayscreen (not illustrated) under the control of CRT controller 24. Increating an image, microprocessor 12 writes data into an area of DRAM16. Various image components can thus be created for screen display.DRAM 16 is also used to store tables of information retrieved from ROMmemory 14.

Some of the data received from other systems on an aircraft are in theform of analog voltages. A/D converter 34 converts these analog signalsfrom analog inputs 36 into binary numbers in order for microprocessor 12to perform calculations. These analog inputs might represent, forexample, the heading output from the aircraft's slaved compass ordirectional gyroscope. Such heading information can be displayed inaddition to the information provided by the features of the inventionset forth below. Associated with A/D converter 34, but not shown, aresignal conditioning circuits and an input multiplexer.

Two connectors 48 are used to connect additional memory to the circuitboard for system 10. This memory is called "external" because it isexternal to a printed circuit board for system 10, although it may becontained in the same assembly. It will typically contain a data basewith information for generating map displays.

Lead 49 from rear connector 32 goes to a system power supply (notshown), preferably of the type disclosed and claimed in copending andcommonly assigned application Ser. No. 100,253, filed on Sept. 23, 1987,by Jon D. Paul, entitled "Improvements in Power Supply Design." Theentirety of the foregoing application is incorporated herein byreference.

Aircraft Landing and Take-Off Areas Shown in True Size and Orientationin Relation to Background Map Data

FIG. 2A shows a screen display 50 of a cathode ray tube, for example,containing map information in accordance with the invention. Screendisplay 50 includes, as referred to herein, an upper display portion 52,a main display portion 53, and a lower display portion 54. Upper andlower display portions 52 and 54 may contain text of useful navigationinformation, such as aircraft heading and ground speed, which may beobtained by known equipment. Main display 53 portrays map data of anarea in which an aircraft vehicle may travel, and a symbol 56 for theaircraft. In the mode of display shown, symbol 56 is centered in maindisplay 53, and remains stationary in the display.

Map display 53 shows an airport 58, designated by the abbreviation"APT". Two runways 60 and 62 are shown in airport 58, and typically areshown if they are greater than 2000 feet in length, regardless ofsurface type. Runways 60 and 62, further, are shown with identifiers ateach runway end, orthogonal to the associated runways and indicating thefirst one or two digits of a magnetic compass heading that a pilot wouldfollow to land on such runway. The identifiers at each runway end arereadable by a pilot except when the displayed range is quite large.

Display 53 further shows a prohibited area 65 in main display 53, andmay represent airspace in which civilian aircraft are prohibited fromflying.

Map display 53 shows airport runways 60 and 62 in true size andorientation with respect to the background map data. The runways areshown in true proportion to the background map data, which changes inscale at user command. In the past, pilots would need to consult twodifferent map sources to determine some of the information shown indisplay 53: one source would give airport location, and the other wouldgive true size and orientation of airport runways. The pilot, however,would still not see a runway in true proportion to background map data.

FIG. 2B illustrates a screen display 50 with main display portion 53showing an aircraft symbol 56 and the surrounding map data reduced insize compared to FIG. 2A. Display 53 of FIG. 2B thus shows a greaterrange of distance than in FIG. 2A. The runways of airport 58 are reducedin size to bear true relation with background map data. Aircraft symbol56 may be reduced in size, also, if desired.

The system hardware described above in connection with FIG. 1 providesthe foregoing screen display features of FIGS. 2A and 2B when programmedin accordance with the flow chart of FIGS. 3A and 3B. Connection pointsin FIGS. 3A and 3B are shown by letters A, B and C.

The start command 300 in FIG. 3A initiates the subroutine described byFIGS. 3A and 3B. In block 302, data of a landing facility is retrievedfrom the data base. Decision block 304 queries whether the landingfacility can be displayed. This may based on geographical location ofthe facility--a local flight over the western United States would notneed to display landing facilities of the eastern United States, forexample. Additionally, the pilot may preselect for display only landingfacilities meeting certain criteria, in accordance with a furtherfeature of the invention.

The "NO" branch from block 304 directs a search for another landingfacility in block 302. The "YES" branch leads to block 306, wherein thelatitude and longitude ("LAT/LON") of the landing facility referencepoint is retrieved from the data base. The reference point is a singlepoint indicating location of a landing facility.

In decision block 308 the question is asked whether the runways have endpoints (i.e. latitude and longitude points) in the data base. If so,such information is obtained from the data base used, as described inblock 310, to calculate the latitude and longitude of the four cornersof the runway. If not, the assumption set forth in block 312 is made.

Block 313 then directs calculation of the X/Y Cartesian coordinatelocation of the runway on screen the display (i.e. on main screen 53 ofFIG. 2A, for example). Such calculation is more fully set forth in thatblock. In block 314, lines are drawn to connect corners of the runway toform an actual image. As queried, in block 316, if the current range ofthe display is less than 20 nautical miles ("NM"), for instance, then,according to block 318, a series of lines is drawn to form the one tothree character identifier of a so-called "base" end of the runway, andin block 320 a similar identifier is drawn at the other end of therunway. FIG. 2A shows an identifier "36" at the lower end of runway 62,for example.

If the current range of display is not less than 20 nautical miles,then, according to block 316, decision block 322 is reached. Block 322is alternatively reached from block 320.

Decision block 322 asks whether there are runway end points. If not,block 324 directs the drawing of the landing facility identifier (e.g.,"APT") in spaced relation to the airport reference point (see block306). If there are runway end points, decision block 326 is reached,asking whether there are more runways. If not, block 324, describedabove, is reached. If so, a pointer to the next runway is set accordingto block 328, and via common connection B, block 310 (FIG. 3A) is againreached.

After exiting block 324, query 330 asks whether there are more landingfacilities. If so, block 302 (FIG. 3A) is reached via common connectionpoint C; if not, a completion block 332 is reached.

Display of Navigation Areas in Relation To Aircraft Symbol

FIG. 4 shows a screen display 50 with a main area 53 similar to that ofFIG. 2B, but also including terminal control area ("TCA") boundaries 66,68 and 70, and their respective altitude notations 67, 69 and 71. TCAaltitude notation 67, i.e., "77/SFC", indicates a ceiling for TCA area66 of 7700 feet, and a floor at the ground surface. Notation 69, i.e.,"77/50", represents the same ceiling, but a floor of 5000 feet, andnotation 71 similarly define the floor and ceiling of area 70.

Boundaries 66, 68 and 70 could represent boundaries of an airport radarservice area ("ARSA"), or other navigational control area, rather than aTCA.

FIG. 4 shows navigation areas 66, 68 and 70, in unique manner, inrelation to aircraft symbol 56.

The system hardware described above in connection with FIG. 1 providesthe foregoing screen display features of FIG. 4 when programmed inaccordance with the flow chart of FIGS. 5A and 5B. Points A, B, C, D andE are common connection points in the flow chart of FIGS. 5A and 5B.

Starting with block 500, the subroutine of FIGS. 5A and 5B firstdetermines minimum and maximum longitudes of the currently displayedarea in block 502. In block 504, the minimum and maximum latitudes for acontrol area are obtained from the data base. At decision block 506,unless some part of the control area is within the display, a nextcontrol area is pointed to in the data base, at block 508. At decisionblock 510, if there are more control areas in the data base, a branch ismade to block 504 for the next control area. If there are no furthercontrol areas, the subroutine finishes at block 512.

Returning to block 506, if any part of the control area is within thedisplay, block 514 directs the setting of a pointer to a first featureof a segment of a control area. If the feature is a line, decision block516 routes the program to block 518 to obtain the latitude and longitudeof the end points of the line. If the feature is an arc, decision block514 routes the program to block 520 to get position and configurationinformation for the arc.

Continuing at FIG. 5B, for a line feature, block 522 coordinates the X/Yplacement of the feature on a screen display, and block 524 directs thedrawing of such line segment. For an arc feature, blocks 526 and 528parallel the foregoing operations of blocks 522 and 524.

At decision block 530, if the feature drawn in blocks 524 or 528 is thefirst feature of a control area segment, block 532 directs the drawingof a ceiling and floor altitude notation near the feature prior tosetting a pointer to the next feature of the control area segment inblock 534; if such feature is not the first feature, the flow chart goesdirectly to block 534.

At decision block 536, if pointer is to the last feature of the controlarea segment, block 538 directs a pointer to the next control areasegment; if the feature is not the last feature, a branch is made todecision block 516 via common connection point D.

At decision block 540, if the next segment is the last segment, a branchis made to block 508 via point B; if not, a branch is made to block 514via point C.

Display of Criteria-Selected Objects

FIGS. 6A, 6B and 6C illustrate a further feature of the invention. FIG.6A shows a main screen display 53 with VORs or other navigational aids76, 77, 78 and 80; and airports 82, 84, 86, 88, 90 and 92. Displayscreen 53 may contain unnecessary or unwanted information that cluttersthe screen. The pilot-user may be interested only in airports 82 and 90,for example, since they may have suitable runways or available fuel,whereas the other runway shown in FIG. 6A may lack such criteria.According to the present feature, the pilot may select criteria, as bypressing front panel buttons (not shown) to display, as shown in FIG.6B, only airports 82 and 90, in addition to the VORs, or othernavigational aids.

If the pilot wishes to remove an entire category of objects, such asVORs 76, 77, 78 and 80, this is accomplished by user command to removeall VORs, resulting in streamlined screen display 53 of FIG. 6C.

The foregoing features can be implemented by programming the hardware ofFIG. 1 according to the flow chart shown in FIG. 7.

In FIG. 7, starting from block 700, block 702 directs the creation of atable of objects from the main data base based on direction of traveland position of an aircraft or other vehicle. A far distant airport, forexample, would not be included in the table of objects of block 702;only those within a reasonable range of travel are included. Objectsshown in the foregoing table are examined one-by-one, in block 704, todetermine whether the object falls within the range of the screendisplay (e.g. 53 in FIG. 6A).

Block 706 requires an object meeting the criteria of block 706 to beexamined to see if it is pre-qualified according to user-selectedcriteria. A pilot-user may wish to display all airports, or only thosewith runway lengths exceeding a given distance, for example.Alternatively, the pilot may want to exclude all navigational aids of aparticular category, which may not be useful for a given flight.

Block 708 directs periodic creation of a new table of objects in block702 based upon vehicle direction of travel and position. Blocks 702 and708 can be seen to cooperate to reduce the amount of data which must besearched in blocks 704 and 706.

Block 710 generally instructs the display of new objects meeting theuser-selected criteria, and a branch is then made back to block 702,indicating that the process is periodically repeated as the monitoredvehicle travels.

Display of Text on Map Data for User-Selected Object

FIG. 8A shows a typical screen display 53 including airports 100 and 102and a VOR 104. A pilot, by front panel switch command, can select any ofobjects 100, 102 or 104 to provide immediate text of such objects indisplay 53.

As shown in FIG. 8B, for example, by selecting airport 100, text 106appears on the screen adjacent to airport 100. Text 106 contains theidentifier "APT" for airport, and the magnetic bearing "BRG" anddistance "DIST" to the airport. Box 108 surrounds text 106 so as tohighlight that text.

Similar text information 110 in box 112 can be provided for VOR 104, asshown in FIG. 8C.

The foregoing features can be implemented on the hardware of FIG. 1 inaccordance with the flow chart of FIGS. 9A and 9B. Common connectionpoints A, B, and C are shown in FIGS. 9A and 9B.

Starting from block 900, block 902 in FIG. 9A directs that the latitudeand longitude of the aircraft, or other monitored vehicle, be obtained.The decision block 904 basically asks whether the display system of theinvention is currently operating in the present mode, and if so, anobject is selected. If there is no such object selected, the flow chartbranches to block 906 via connection point A to search a table ofdisplayed objects to find the nearest object to the aircraft. Then block926 is reached, and will be discussed below.

Returning to decision block 904, if an object is currently selected,block 910 requests that the latitude and longitude of the currentlyselected object be obtained, and block 912 directs calculation of thedistance to the currently selected object.

Decision block 914 requests whether the next farther or the next nearerobject has been requested. If a farther object has been requested, abranch to block 916 via point B selects a search of a table of displayedobjects for the next object farther than the current object. If there isa farther object, decision block 918 directs a branch to block 926, asdiscussed below. If no farther object can be found, decision block 918branches to block 906 to search instead for the nearest object to theaircraft.

Returning to decision block 914, if the user has requested a nearerobject than the current one displayed, a branch is made to block 920,via point C, to search the table of displayed objects for the nextobject nearer than the current object. If such an object exists,decision block 922 branches to block 926, discussed below. If not,decision block 922 branches to block 924 to search the table ofdisplayed objects for the farthest object from the aircraft, and thenblock 926 is reached, as discussed below.

Block 926 directs the saving of a pointer to the object now selected forfuture use in connection with the flow chart of FIG. 11A, discussedbelow. Decision block 908 is then reached.

Decision block 908 concerns the type of object located. If the object isof a type wherein the bearing from the object to the aircraft iscalculated, block 928 directs such calculation; if the object is of theconverse type with the bearing to the object from the aircraftcalculated, block 930 directs such calculation. Blocks 928 and 930 alsocalculate the distance between object and aircraft.

After the calculations of either block 928 or 930 are completed, block932 directs the display of the bearing and distance under an objectidentifier in a screen display and, further, to highlight suchinformation, directs a box to be drawn around the identifier, bearingand distance. As the aircraft moves, block 932 directs continual updateof such bearing distance. Block 934 directs the drawing of the object'sidentifier below the main display, e.g. in lower display 54 of FIG. 8A.Completion block 936 is then reached.

Display of Text Concerning User-Selected Object

FIG. 10A shows text 120 for airport 100 of FIG. 8B, for example. Text120 may include such information as set forth on screen display 53("ELEV"=elevation; "VAR°"=magnetic variation; "ID"=identifier;"RAD"=radial; "DIST"=distance; "LEN"=length; "WID"=width;"ILS"=instrument landing system.) Text 120 is for an airport, whereastext 122 of FIG. 10B is for a navigational aid such as a VOR or VORTAC.

The foregoing features may be implemented on the hardware of FIG. 1 inaccordance with the flow charts of FIGS. 11A and 11B. Common connectionpoints A and B are shown in FIGS. 11A and 11B.

Starting from block 1100 in FIG. 11A, block 1103 directs a pointer tothe currently selected object. When using the flow chart of FIGS. 9A and9B, the pointer is already set in block 926 of FIG. 9B. This permits theuser to select a specific object with a command non-specific to suchobject, making operation easier.

Decision block 1106 asks whether the object is a landing facility or anavigational aid ("NAVAID"). If a navaid, block 1107 directs thatcompressed data be obtained from the data base, decoded and displayed intext form for information of the type contained in block 1107.

The compressed data for the text of block 1107 is preferably used toconserve memory space.

Further information about the navigational aid may then be obtained byusing the continuing flow chart. If the navaid is a VOR, VORTAC, orTACAN, as queried by block 1108, block 1110 directs calculation of thebearing from the object to the aircraft and the distance to the object.If not, block 1112 directs calculation of the bearing to the object fromthe aircraft and the distance to the object. Block 1114 then directsdisplay of the calculated bearing and distance from block 1110 or 1112,and block 1116 further asks whether the object is a instrument landingsystem ("ILS") or a FAN MARKER system. If so, the present subroutine iscompleted, as shown by block 1118. If the decision from block 1116 is"NO", the further question is asked in block 1120 whether the object isa TACAN. If so, block 1122 directs the display of the TACAN's channelnumber, and then the completion block 1118 is reached. If not, thefrequency of the object is displayed according to block 1124, and thefurther question is asked in block 1126 whether the object is a VOR orVORTAC. If not, the completion block 1128 is reached. If so, the channelof the VOR or VORTAC is displayed according to block 1130, and then thecompletion block 1128 is reached.

Returning to decision block 1106 (FIG. 11A), if the selected object is alanding facility, block 1132 directs that compressed data be obtainedfrom the data base, decoded and displayed as text, such as set forth inblock 1132.

Block 1134 requests additional, useful information, set forth in thatblock, of the nearest VORTAC to the landing facility. The completionblock 1136 is then reached.

If still further text is requested for the selected landing facility,according to user command, a further screen of text can be provided inaccordance with the flow chart following block 1138.

Decision block 1140 asks whether there are any more runways at theselected airport. If not, decision block 1142 asks whether text of anyrunways has been displayed on the current page or screen. If so,completion block 1144 is reached. If not, a branch is made via point Bto block 1132 to replace the displayed runway data with general dataabout the landing facility. Decision block 1140 may then be reachedagain if the user requests more information in block 1138. If there aremore runways, decision block 1144 then asks whether the text of threerunways has been displayed on the current "page", or screen. If so,completion block 1146 is reached. If not, block 1148 creates the displayof the runway identifier, length, width, surface, lighting andinstrument landing system for that runway. Decision block 1140 is thenrevisited.

Alert for Increased Oncoming Minimum Safe Altitude

In FIG. 12, screen display 53 shows, as typical objects, VOR 130 andairport 132. A minimum safe altitude ("MSA") notation 134, followed by amean sea level ("MSL") notation 136, appears in the lower screen display54. MSA 134 is the highest MSA for the range displayed on main screen53, although it could be for more or less than the full displayed range.

To obtain the MSA for a given range, the MSA for each 30 by 30 nauticalmile square, e.g., in a grid is read as long as such square lies partlyor totally in the given range.

A larger-than displayed range is scanned to search for an MSA that isgreater than 1000 feet, or some other distance, above the currentlydisplayed MSA 134. Aircraft symbol 56 is preferably located less thanone-third the way from bottom to top of main display 53, e.g., one-fifththe way as shown, so that the scanned area lies mostly in front of themonitored aircraft.

In accordance with the present feature, MSA notation 134 is highlightedby having MSL notation 136 appear in reverse video, similar to aphotographic negative, rather than as a normal, positive image. Thisalerts the pilot of the danger that lies ahead.

The foregoing features may be implemented on the hardware of FIG. 1 inaccordance with the flow chart of FIG. 13.

Starting at block 1300 in FIG. 13, block 1302 directs that the currentlatitude and longitude of the monitored aircraft be obtained. Block 1304directs calculation of the latitude and longitude limits of the displayat the currently selected range. Block 1306 then requires the reading ofall the entries in the minimum safe altitude ("MSA") table which liepartly or totally within the limits obtained in block 1304. The largestentry is also stored. Block 1308 directs the display of the largest MSAon the screen, typically in lower display 54 of FIG. 12.

Block 1310 then directs that the latitude and longitude limits of thelargest range selectable in the current display mode be calculated. Thepurpose is to obtain a larger-than-displayed range in which to searchfor increased MSAs; therefore, a larger-than-displayed range could beselected in a different way. Block 1312 then directs that all theentries in the MSA table which lie partly or totally within thelarger-than-displayed range be read, and that the largest entry bestored.

Decision block 1314 asks whether the largest MSA in thelarger-than-displayed range is more than a thousand feet, or some otherdistance, above the MSA that is currently displayed. If so, an alert isprovided. This may be done by displaying the mean sea level ("MSL")notation, which follows a normally displayed MSA, in reverse video(i.e., like a photograph negative), according to block 1316.

If the largest MSA in the larger-than-selected range is not more than athousand feet above the currently displayed MSA, block 1317 directsdisplay of the MSL term in normal video (i.e., like a photographpositive) after the normally displayed MSA.

The subroutine is completed at block 1318, but is periodically repeatedas the monitored aircraft travels.

Moving Aircraft on Stationary Background

FIG. 14A shows screen display 53 centered on a preselected "waypoint",or object along the way, 150. The pilot preferably preselects waypoint150 by inputting identifying data (e.g., latitude and longitude) througha LORAN C receiver, which then sends such information through RS-232Cinput 18 (FIG. 1) to the hardware system 10. The waypoint identifyinginformation could also be supplied to the hardware system of FIG. 1 fromother navigational equipment onboard the aircraft.

Waypoint 150 in FIG. 14A is an airport. An arrow 152 near the edge ofdisplay 53 indicates the bearing of the monitored aircraft. The positionof the aircraft is outside the displayed range in FIG. 14A; therefore,arrow 152, different from symbol 56 in FIG. 2A, for example, is used torepresent the monitored aircraft. In FIG. 14A, the background map dataremains stationary and arrow 152 represents the aircraft. Display 53 istypically oriented with north towards the top center of the display.

When the monitored aircraft comes within the displayed range of maindisplay 53, a different aircraft symbol 152' is used, to show movementof the aircraft.

The foregoing features can be implemented on the hardware of FIG. 1 inaccordance with the flow chart of FIGS. 15A and 15B. Points A and B arecommon connection points in FIGS. 15A and 15B.

Starting at block 1500 in FIG. 15A, block 1502 instructs the calculationof the latitude and longitude of a preselected waypoint from the LORANreceiver to provide a reference point. The waypoint is a user-selectedobject or arbitrary location, which is contained in the screen display.According to block 1504, such reference point is preferably at thecenter of the display. Block 1506 directs the calculation of thelatitude and longitude ("LAT/LON") limits of the display based on thefactors set forth in that block. Block 1508 then directs the search ofthe data base for suitable objects for display within the latitude andlongitude limits calculated in block 1506. Suitable objects may be thosemeeting previously selected user criteria, for example, according to afeature of the invention described above in connection with FIGS. 6A,6B, 6C and 7.

Decision block 1510 asks whether a landing facility, navigational aid,or control area has been found.

If an object has been found, block 1512 directs the drawing of theobject according to the criteria set forth in that block. The drawing isdone in an area of memory not viewable by the cathode ray tube display.A branch is then made from block 1512 to block 1508 via connection pointA to search for another object for display.

When decision block 1510 is reached with a negative answer, block 1514directs the copying of the completed map to an area of memory directlyviewable on the cathode ray tube display. Block 1514 explains that thisleaves two identical copies of the map in memory with no plane, oraircraft, drawn on the visible map.

Block 1516 then asks if the location of the plane is on the display. Ifso, block 1518 directs the drawing of the plane on the viewable map inits true position relative to the waypoint and block 1520 causes aperiodic recycling back to decision block 1516 to update the display.

If the location of the plane is not on the display, block 1516 branchesto block 1522, which directs the drawing of an arrow near the edge ofthe display to represent the oncoming direction of flight of the planetowards the waypoint.

Emergency Display of Nearest Suitable Airports

FIG. 16A shows a typical screen display 53, with aircraft symbol 160 anda typical airport 162. If an emergency develops and the aircraft mustland quickly, a user command will produce screen display 50 of FIG. 16B.Main display 53 shows at least five airports 162, 164, 166, 168 and 170suitable for landing, according to preselected user criteria. The rangeof display 53 is automatically adjusted to include such suitableairports.

Screen display 53 also shows the nearest VOR, VORTAC or similarnavigational aid 172 and, at lower portion 174 of main display 53, forexample, also shows an identifier for the navigational aid ("NAVAID"),and the radial and distance from such navigational aid to the monitoredaircraft. Normal text information in upper and lower displays 52 and 54is preferably deleted; the bearing and distance to the closest airportare displayed in the upper display 52; and the airport identifier andcommunication frequency for the airport are displayed in the lowerscreen display 54. Such text information can obviously be arranged indifferent ways.

By a scrolling command, the pilot may select any other of the displayedairports to obtain upper and lower screen displays 52 and 54 of textspecific to the newly selected airport.

The foregoing features may be implemented on the hardware of FIG. 1 inaccordance with the flow chart of FIGS. 17A and 17B. Connection point Ais common between FIGS. 17A and 17B.

Starting at block 1700 in FIG. 17A, block 1702 directs a search throughthe data base to create a list of all landing facilities andnavigational aids within a predetermined radius satisfying preselectedminimum requirements for safe operation. When establishing a flightplan, the user will typically select the requirements for safeoperation, such as minimum runway length, and lighting for nightlanding.

Block 1704 directs a search through the list created in block 1702 andselects the smallest range including at least a predetermined number ofusable landing facilities. Block 1706 directs the drawing of a displayin which a plane symbol is centered, for example, at the rangeautomatically chosen in block 1704.

Block 1708 then directs the search through the list established in block1702 for the closest VOR or VORTAC. Block 1708 also directs theselection of the closest landing facility to the aircraft, from the listof block 1702.

Block 1710 then directs the calculation of the distance and bearing fromthe closest VOR or VORTAC, or similar navigational aid, to the aircraft.Block 1712 then directs the display of the identifier, bearing anddistance of the VOR or VORTAC (or similar navigational aid). Suchdisplay is typically placed at the lower part of the main display, suchas in area 174 shown in FIG. 16B. Block 1712 also directs a continuedupdate of such bearing and distance as the vehicle moves.

Block 1714 directs display of the identifier and communicationsfrequencies for the selected landing facility, and such display may alsobe below the main screen display. Block 1716 directs the calculation ofthe distance and bearing from the aircraft to the selected landingfacility, and block 1718 directs display of such information, which maybe above the main display.

As the plane moves, block 1718 also directs the continual updating ofsuch bearing and distance information, and the completion step is thenreached at block 1720.

Display of Projected and Actual Flight Patterns

FIG. 18A shows a screen display 53 with a projected flight pattern 180shown in dashed line form. Main display 53 may include map data, such asin FIG. 14A, and any map data and projected flight pattern 180 arepreferably held stationary in the display. Aircraft symbol 182 thenmoves about display 53, in the same way described above with respect toFIGS. 14A and 14B. As the monitored aircraft proceeds toward and alongprojected flight pattern 182, an actual flight pattern 184 of where ithas flown is generated, as shown in FIG. 18B.

The foregoing features can be implemented on the hardware of FIG. 1 byincluding sufficient nonvolatile memory in the data base board 36 tostore the projected and actual flight pattern.

The foregoing describes a map display system with various features thatcan be used alone or together. The map display system is particularlyuseful for an airborne vehicle, since it conveys to a pilot-user a largeamount of relevant, easy-to-read information in a brief period of time.The system, further, incorporates safety features tailored fornavigation of an airborne vehicle.

Although the present invention has been described in connection with aplurality of preferred embodiments thereof, many other variations andmodifications will now become apparent to those skilled in the art. Itis preferred, therefore, that the present invention be limited not bythe specific disclosure herein, but only by the appended claims.

What is claimed is:
 1. Map display system for navigation of a vehicleshowing selected map features in true size and orientation in relationto background map data, the system comprising:memory means to store mapdata of an area in which the vehicle may travel; such data includingbackground map data in a first memory location; reference locationpoints of selected map features in a second memory location, and truesize and orientation data of such selected map features in a thirdmemory location; first means to selectively collect background map datafrom the memory means and to compose a first image component of suchdata; second means to selectively collect from the memory meansreference location points of one or more individual features from theselected map features and true size and orientation data of the one ormore selected features within the range of the first image component andto compose a second image component of the one or more selected mapfeatures aligned with and in true size proportion to the first imagecomponent; and display means to collectively display the first andsecond image components.
 2. The map display system of claim 1, whereinthe vehicle comprises an aircraft and the selected map features compriseaircraft landing and take-off areas.
 3. The map display system of claim2, further comprising:third means to compose a third image component ofa symbol for the aircraft; means to receive position and direction oftravel data for the aircraft and to determine placement of the thirdimage component relative to the first and second image components; andmeans included in the display means to display the third image componentalong with the first and second image components.
 4. The map displaysystem of claim 2, wherein the landing and take-off areas compriserunways, the memory means comprises means to store identifiers of runwayends, and the second means includes means to collect data of suchidentifiers and to include the same in the second image component. 5.The map display system of claim 3, wherein the first and second meansinclude respective means to repeatedly recompose the first and secondimage components to show movement of such image components, and thethird means includes means to maintain the third image component instatic position.
 6. The map display system of claim 3, wherein the firstand second means include respective means to hold the first and secondimage components in static position, and the third means includes meansto repeatedly recompose the third image component to show movement ofthe aircraft symbol.